Polysaccharide (starch, glycogen or the like) contained in food is hydrolyzed by α-amylase in saliva and pancreas and converted into oligosaccharide such as maltose, isomaltose or the like, then decomposed to glucose by disaccharide degrading enzyme such as α-glucosidase or the like in the small intestine and absorbed.
Thus, α-amylase and α-glucosidase perform an important role as a digestive enzyme for carbohydrate in the body. These enzyme activities affect the blood glucose level. Therefore, it is important to control these enzyme activities for the preventions and medical treatments of diabetes mellitus and obesity.
There are two different types of diabetes mellitus. One is insulin-dependent diabetes mellitus (Type I diabetes) and the other is non-insulin dependent diabetes mellitus (Type II diabetes), and the latter type accounts for more than 90% in the incidence of diabetes mellitus.
The latter type (Type II diabetes) is caused by derangement of carbohydrate and fat metabolism arising from an insufficient insulin action (for instance, insulin-hyposensitivity in the organ, insulin-hyposecretion in pancreas or the like) due to overeating.
Non-insulin dependent diabetes mellitus (Type II diabetes) should be basically controlled by diet therapy or exercise therapy rather than medication. However, such self-control does not always correct the aforementioned metabolic derangement, and medication is very much counted on.
However, it is necessary to consider side effects, dosage and usage of the medicine. In general, medicine is usually an intermixture of various components. Therefore, it is necessary to consider the side effect each component has and adverse effect caused by a prolonged dosage of each component.
Extract from gymnema leaf, guava leaf, banaba leaf, mulberry leaf or the like is widely known as a plant-derived extract which is effective to correct the derangement of carbohydrate metabolism. From the viewpoint of safety, these plant-derived extracts are easily applied to food, drugs and medicines, or the like, therefore effective components or the like of the said plant-derived extracts are now being extensively researched.
Against this background, the inventors in this invention have been investigating contents of polyphenol, SOD-like activities or the like in regard to the various plant-derived extracts, then finally came to focus on ethanol extract of evening primrose seed.
After each of the aforementioned experiments has been conducted, they came to know the fact that this extract contains various polyphenol effective to inhibit the carbohydrate absorption.
This invention aims at providing inhibitor of carbohydrate absorption derived from evening primrose seed and method for manufacturing the said inhibitor of carbohydrate absorption which are significantly effective to prevent or relieve symptoms of diabetes mellitus and to prevent obesity.